Apparatus for guiding a control cable

ABSTRACT

An apparatus for guiding a cable includes a frame and a cable guide member mounted to the frame for rotation around a guide member axis. The cable guide member includes a curved outer peripheral cable guide surface disposed radially outwardly from the guide member axis for guiding the cable. A bearing having a cable guide surface is disposed radially outwardly from the outer peripheral cable guide surface. When the cable guide member has a small radius of curvature, the cable may contact the bearing and thus avoid the excessive friction encountered in the prior art.

BACKGROUND OF THE INVENTION

The present invention is directed to mechanical control cable mechanismsand, more particularly, to an apparatus for guiding a control cable thatmay be used to control brake or gear shifting devices on a bicycle.

Bicycle brake and shifting devices frequently use control cables of thetype wherein an inner cable slides within an outer casing. Such controlcables usually are connected between a controlling device, such as brakelever, a shifting lever or twist grip shifter, and a controlled devicesuch as a brake or a transmission. Since the controlled deviceordinarily is located at some distance from the controlling device, andsince the controlled device ordinarily is mounted at a fixed positiondetermined by the configuration of the bicycle, the control cable oftenmust follow a curved path from the controlling device to the controlleddevice. Unfortunately, when the cable must follow a steep curve, theouter casing sometimes cannot bend satisfactorily, or else the frictionbetween the inner cable and the outer casing caused by the curve becomesexcessive. As a result, such steep curves cannot be accommodated by thecontrol cable.

One technique used to overcome the problem of bending the outer casingto follow sharp curves involves using a roller mounted on a frame,wherein the radius of curvature of the outer peripheral surface of theroller is set to match the required curve. The frame may include a cableentry portion and a cable exit portion, wherein the inner wire entersthe cable entry portion, passes around the roller, and exits the cableexit portion. While this technique is satisfactory for manyapplications, the radius of the roller can not be made too small becausethe inner cable also resists bending. For example, when an inner wire isconstructed of multiple strands wound together, the optimum radius ofthe roller is 200 times the diameter of a single strand. For a typicalstrand diameter of 0.32 millimeters, the optimum roller radius thenwould be approximately 64 millimeters. Such a roller is extremely largeand would be unacceptable for many applications. Consequently, smallerrollers are used despite the fact that such smaller rollers are notpreferred. However, even though the inner cable may be forced to passover the outer peripheral surface of such a smaller roller, the innercable resists such bending and tends to rub against the cable entryportion and the cable exit portion of the frame. The smaller the radiusof the roller, the greater the resistance to bending by the wire, andthe greater the rubbing. Such rubbing can cause excessive friction, thuseliminating the benefit of using a roller to guide the inner cablearound steep curves.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus for guiding a controlcable of the type wherein the cable may be guided around steep curveswithout excessive friction. In one embodiment of the present invention,an apparatus for guiding a cable includes a frame and a cable guidemember mounted to the frame for rotation around a guide member axis. Thecable guide member includes a curved outer peripheral cable guidesurface disposed radially outwardly from the guide member axis forguiding the cable. A bearing having a cable guide surface is disposedradially outwardly from the outer peripheral cable guide surface. Whenthe cable guide member has a small radius of curvature, the cable maycontact the bearing and thus avoid the excessive friction encountered inthe prior art.

In another embodiment of the present invention, an apparatus for guidinga control cable includes a frame and a cable guide member mounted to theframe for rotation around a guide member axis. The cable guide memberincludes a curved outer peripheral cable guide surface disposed radiallyoutwardly from the guide member axis for guiding the cable. A firstbearing having a first bearing cable guide surface is disposed radiallyoutwardly from the outer peripheral cable guide surface, and a secondbearing having a second bearing cable guide surface is disposed radiallyoutwardly from the outer peripheral cable guide surface. The firstbearing is spaced apart from the second bearing in a circumferentialdirection of the outer peripheral cable guide surface. When the cableguide member has a small radius of curvature, the cable may contact thefirst and second bearings and again avoid the excessive frictionencountered in the prior art.

In a more specific embodiment, the frame includes a first cable duct anda second cable duct. The first cable duct includes a first opening thattangentially aligns with the outer peripheral cable guide surface of thecable guide member, and the second cable duct includes a second openingthat tangentially aligns with the outer peripheral cable guide surfaceof the cable guide member. The inner wire passes through the first cableduct, passes around the outer peripheral guide surface of the cableguide member and passes through the second cable duct. The first bearingis aligned between the first cable duct and the outer peripheral guidesurface of the cable guide member, and the second bearing is alignedbetween the second cable duct and the outer peripheral guide surface ofthe cable guide member. The bearings are thus positioned for maximumreduction of friction when the outer peripheral cable guide surface hasa small radius of curvature. If desired, the first and second bearingsmay comprise first and second rollers which accommodate the cable withvery small friction.

In another embodiment of the present invention, an apparatus for guidinga cable includes a frame and a cable guide member mounted to the framefor rotation around a guide member axis. The cable guide member includesa curved outer peripheral cable guide surface disposed radiallyoutwardly from the guide member axis for guiding the cable, wherein thecable guide surface terminates at first and second ends. The cable guidemember includes a first abutment and the frame includes a secondabutment for contacting the first abutment and for limiting a range ofmotion of the cable guide member. In a more specific embodiment, thecable guide member and the cable guide surface each has an approximatelysemicircular shape. The cable guide member includes a bounded openingforming a first abutment and a second abutment, and the frame includes aprojecting member which forms a third abutment disposed between thefirst and second abutments for contacting the first and second abutmentsand for limiting a range of motion of the cable guide member. A cableguide member constructed in this manner has a reduced size and weightover prior art structures.

A cable guide constructed according to the present invention may be usedwherever cable bends are desired. For example, the cable guide may bepositioned at a controlling device such as a brake lever, shiftinglever, twist grip shifter or other controlling device. Alternatively,the cable guide may be positioned at a controlled device such as a brakearm, hub brake, derailleur, internal hub transmission, or othercontrolled device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross sectional front view of a particularembodiment of a cable guide according to the present invention;

FIG. 2 is a rear view of the apparatus shown in FIG. 1;

FIG. 3 shows the apparatus of FIGS. 1 and 2 attached to a brake arm;

FIG. 4 shows the apparatus of FIGS. 1 and 2 attached to a control lever;and

FIG. 5 shows the apparatus of FIGS. 1 and 2 attached to a derailleur.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a partial cross sectional front view of a particularembodiment of a cable guide 10 according to the present invention, andFIG. 2 is a rear view of cable guide 10. As shown in those Figures,cable guide 10 includes a frame 14 having a first cable duct 18 and asecond cable duct 22. In this embodiment, first and second cable ducts18 and 22 are formed as tubular members having first and second cableduct openings 26 and 30. As shown in FIGS. 1 and 3, first cable ductopening 26 is sized for receiving an outer casing 40 of a control cable42 therein, and second cable duct opening 30 is sized for receiving aninner cable 34 of control cable 42 therethrough.

A cable guide member 50 having a curved outer peripheral cable guidesurface 54 is mounted to frame 14 through a pivot shaft 58 for rotationaround a guide member axis X. In this embodiment, cable guide member 50and cable guide surface 54 each has a roughly semicircular shape andincludes openings 60, 62 and 64 to reduce the size and weight of thestructure. Opening 62 includes abutments 65 and 66 which cooperate withan abutment formed by a stop pin 44 extending from a side of frame 14 tolimit the range of motion of cable guide member 50. Opening 62 shouldhave an angular distance that corresponds roughly to the intended cablestroke. Stop pin 44 and abutments 65 and 66 allow the use of a cableguide member 50 having a semicircular shape without the risk of theinner cable 34 falling off the cable guide surface 54.

A first bearing in the form of a first roller 70 is mounted to frame 14through a pivot shaft 74 for rotation around a first roller axis Y, anda second bearing in the form of a second roller 78 is mounted to frame14 through a pivot shaft 80 for rotation around a second roller axis Z,wherein guide member axis X, first roller axis Y and second roller axisZ are substantially parallel to each other. Roller 70 is disposedradially outwardly from outer peripheral cable guide surface 54 in closeproximity to first cable duct 18 and is aligned between first cable duct18 and outer peripheral cable guide surface 54. Similarly, roller 78 isdisposed radially outwardly from outer peripheral cable guide surface 54in close proximity to second cable duct 22 and is aligned between secondcable duct 22 and outer peripheral cable guide surface 54. In thisembodiment, cable guide member 50, first roller 70 and second roller 78are completely exposed on frame 14.

As shown in FIG. 1, first and second cable duct openings 26 and 30 bothare substantially tangentially aligned with outer peripheral cable guidesurface 54. Furthermore, first and second rollers 70 and 78 includerespective first and second cable guide surfaces 86 and 88 that liesubstantially in the same plane as outer peripheral cable guide surface54. In this embodiment, first and second rollers 70 and 78 arepositioned at substantially the same radial distance from guide memberaxis X. Inner cable 34 passes through first cable duct opening 26,passes around outer peripheral cable guide surface 54, and passesthrough second cable duct opening 30. If outer peripheral cable guidesurface 54 has a small radius of curvature and therefore defines a steepcurve such that inner cable 34 resists bending around outer peripheralcable guide surface 54, then inner cable 34 will contact first cableguide surface 86 and/or second cable guide surfaces 88. Unlike prior artstructures, very little friction is created between inner cable 34 androllers 70 and 78, so cable performance is not adversely affected. Inthis embodiment, cable guide member 50 may have a radius of 17.5millimeters or more, preferably 19.2 millimeters, or 20 millimeters tothe centerline of the inner cable.

FIG. 3 shows cable guide 10 mounted to a brake assembly 100. In thisembodiment, brake assembly 100 includes a brake arm 104 and a brake arm106. A brake shoe 108 is mounted to an intermediate portion of brake arm104, and a brake shoe 110 is mounted to an intermediate portion of brakearm 106. A connecting link 114 having a mounting flange 115 is pivotablymounted to the upper end of brake arm 104 through a pivot shaft 118, anda wire connector 122 is disposed at the upper end of brake arm 106.Frame 14 of cable guide 10 is mounted to connecting link 114 byinserting second cable duct 22 into mounting flange 115. Outer casing 40of a control cable 42 is fitted within first cable duct opening 26, andthe end of inner cable 34 is fixed to wire connector 122. A sealingmember 116 is fitted around second cable duct 22 and inner wire 34 tohelp prevent contaminants from entering second cable duct 22. As aresult of cable guide member 50, first roller 70 and second roller 78,inner cable 34 bends around an angle of approximately 90° with littlefriction as it proceeds from brake arm 104 to brake arm 106.

FIG. 4 shows the cable guide 10 mounted to a control lever assembly 200.In this embodiment, a mounting bracket 204 is structured for mounting acontrol member such as a brake lever 208 to a handlebar H. Brake lever208 is pivotably mounted to mounting bracket 204 through a pivot shaft212, and mounting bracket 204 includes a cable adjustment barrel 216having a barrel opening 220 through which inner cable 34 passes. Frame14 of cable guide 10 is mounted to mounting bracket 204 by insertingsecond cable duct 22 into barrel opening 220. As a result of cable guidemember 50, first roller 70 and second roller 78, inner cable 34 bendsaround an angle of approximately 90° with little friction as it proceedsfrom first cable duct 18 to the cable attachment point (not shown) onlever 208.

FIG. 5 shows the cable guide 10 mounted to a derailleur 300. Derailleur300 may be a conventional derailleur that includes a base member 304which mounts derailleur 300 to a bicycle frame (not shown), link members308 and 312, and a movable member 316 supporting a chain guide 320. Basemember 304, link members 308 and 312, and movable member 316 areconnected together in the conventional way to form a four-bar linkagemechanism for guiding chain guide 320 among a plurality of sprockets(not shown) mounted to a rear wheel of the bicycle. Of course, theinvention also could be applied to a front derailleur, and derailleursother than a four-bar linkage type may be used as well. In thisembodiment, first cable duct 18 and second cable duct 22 form an acuteangle, rather than the 90° angle formed in the previous embodiments.Frame 14 of cable guide 10 is mounted to derailleur 300 by insertingsecond cable duct 22 into an opening 322 of a cable guide 324 formed inbase member 304. In a conventional derailleur, opening 322 ordinarily issized for receiving outer casing 40 of control cable 42, so second cableduct 22 has approximately the same outside diameter as outer casing 40.Inner cable 34 of control cable 42 passes through cable guide 324 andattaches to a cable connector 330 fixed to the side of link 308. As aresult of cable guide member 50, first roller 70 and second roller 78,inner cable 34 can bend around a very acute angle (or any desired angle)with little friction as it proceeds from first cable duct 18 to cableconnector 330.

While the above is a description of various embodiments of the presentinvention, further modifications may be employed without departing fromthe spirit and scope of the present invention. For example, cable guidemember 50 may be formed as a full circle as shown in phantom in FIG. 1instead of a semicircle. Cable guide member may be formed as a solid,and stop pin 44 may be omitted. Frame 14 may be formed to cover part orall of cable guide member 50, first roller 70 or second roller 78 ratherthan leaving these components exposed. Rollers 70 and 78 may be replacedby solid members having low coefficients of friction. First cable duct18 and second cable duct 22 may be shaped to mate with any desiredstructure, and they may be placed at whatever orientation is desired tomake the inner cable bend at the desired angle. The components may beformed from many different materials. For example, cable guide member50, first roller 70 and second roller 78 may be formed from POM, andframe 14 may be formed from aluminum. Thus, the scope of the inventionshould not be limited by the specific structures disclosed. Instead, thetrue scope of the invention should be determined by the followingclaims.

What is claimed is:
 1. An apparatus for guiding a cable comprising:aframe; a cable guide member mounted to the frame for rotation around aguide member axis, wherein the cable guide member includes a curvedouter peripheral cable guide surface disposed radially outwardly fromthe guide member axis for guiding the cable; a bearing disposed radiallyoutwardly from the outer peripheral cable guide surface, wherein thebearing has a bearing cable guide surface; and wherein the bearingcomprises a roller that rotates around an axis substantially parallel tothe guide member axis.
 2. The apparatus according to claim 1 wherein theframe includes a cable duct having a duct opening that aligns betweenthe outer peripheral cable guide surface and the bearing, and whereinthe bearing is aligned between the cable duct and the outer peripheralguide surface.
 3. The apparatus according to claim 2 wherein the ductopening substantially tangentially aligns with the outer peripheralcable guide surface.
 4. The apparatus according to claim 1 wherein thecable guide surface terminates at a radially inwardly extending abutmentwhen viewed along the guide member axis.
 5. The apparatus according toclaim 4 wherein the cable guide surface has a substantially semicircularshape when viewed along the guide member axis.
 6. An apparatus forguiding a cable comprising:a frame; a cable guide member mounted to theframe for rotation around a guide member axis, wherein the cable guidemember includes a curved outer peripheral cable guide surface disposedradially outwardly from the guide member axis for guiding the cable; afirst bearing comprising a first roller disposed radially outwardly fromthe outer peripheral cable guide surface for rotation around a firstaxis substantially parallel to the guide member axis, wherein the firstbearing has a first bearing cable guide surface; a second bearingcomprising a second roller disposed radially outwardly from the outerperipheral cable guide surface for rotation around a second axissubstantially parallel to the guide member axis, wherein the secondbearing has a second bearing cable guide surface; and wherein the firstbearing is spaced apart from the second bearing in a circumferentialdirection of the outer peripheral cable guide surface.
 7. The apparatusaccording to claim 6 wherein the outer peripheral cable guide surface,the first bearing cable guide surface and the second bearing cable guidesurface lie in a common plane.
 8. The apparatus according to claim 6wherein the cable guide surface terminates at a radially inwardlyextending abutment when viewed along the guide member axis.
 9. Theapparatus according to claim 8 wherein the cable guide surface has asubstantially semicircular shape when viewed along the guide memberaxis.
 10. The apparatus according to claim 6 wherein the frame includesa first cable duct and a second cable duct.
 11. The apparatus accordingto claim 10 wherein the first cable duct comprises a first tubularmember through which the cable passes, and wherein the second cable ductcomprises a second tubular member through which the cable passes. 12.The apparatus according to claim 10 wherein the first cable ductincludes a first opening that substantially tangentially aligns with theouter peripheral cable guide surface, and wherein the second cable ductincludes a second opening that substantially tangentially aligns withthe outer peripheral cable guide surface.
 13. The apparatus according toclaim 10 wherein the first bearing is disposed in close proximity to thefirst cable duct, and wherein the second bearing is disposed in closeproximity to the second cable duct.
 14. The apparatus according to claim10 wherein the first bearing is aligned between the first cable duct andthe outer peripheral guide surface, and wherein the second bearing isaligned between the second cable duct and the outer peripheral guidesurface.
 15. The apparatus according to claim 14 wherein the first cableduct includes a first opening that substantially tangentially alignswith the outer peripheral cable guide surface, and wherein the secondcable duct includes a second opening that substantially tangentiallyaligns with the outer peripheral cable guide surface.
 16. The apparatusaccording to claim 10 wherein the first cable duct is spaced apart fromthe second cable duct.
 17. The apparatus according to claim 16 whereinthe first cable duct comprises a first tubular member through which thecable passes, and wherein the second cable duct comprises a secondtubular member through which the cable passes.
 18. The apparatusaccording to claim 17 wherein the cable guide member is substantiallyexposed.
 19. The apparatus according to claim 18 wherein the first andsecond rollers are substantially exposed.
 20. The apparatus according toclaim 6 wherein the cable guide surface terminates at first and secondends.
 21. The apparatus according to claim 20 wherein the cable guidesurface has an approximately semicircular shape.
 22. The apparatusaccording to claim 20 wherein the cable guide member has anapproximately semicircular shape.
 23. The apparatus according to claim20 wherein the cable guide member includes a first abutment, and whereinthe frame includes a second abutment for contacting the first abutmentand for limiting a range of motion of the cable guide member.
 24. Theapparatus according to claim 23 wherein the cable guide member includesa bounded opening which forms the first abutment, and wherein the frameincludes a projecting member which forms the second abutment.
 25. Theapparatus according to claim 20 wherein the cable guide member includesa first abutment and a second abutment, and wherein the frame includes athird abutment disposed between the first and second abutments forcontacting the first and second abutments and for limiting a range ofmotion of the cable guide member.
 26. The apparatus according to claim25 wherein the cable guide member includes a bounded opening which formsthe first and second abutments, and wherein the frame includes aprojecting member which forms the third abutment.
 27. An apparatus forguiding a cable comprising:a frame; a cable guide member mounted to theframe for rotation around a guide member axis, wherein the cable guidemember includes a curved outer peripheral cable guide surface disposedradially outwardly from the guide member axis for guiding the cable; afirst bearing comprising a first roller disposed radially outwardly fromthe outer peripheral cable guide surface, wherein the first bearing hasa first bearing cable guide surface; a second bearing comprising asecond roller disposed radially outwardly from the outer peripheralcable guide surface, wherein the second bearing has a second bearingcable guide surface; wherein the first bearing is spaced apart from thesecond bearing in a circumferential direction of the outer peripheralcable guide surface; and wherein the first bearing and the secondbearing are disposed at the same radial distance from the guide memberaxis.
 28. An apparatus for guiding a cable comprising:a frame; a cableguide member mounted to the frame for rotation around a guide memberaxis, wherein the cable guide member includes a curved outer peripheralcable guide surface disposed radially outwardly from the guide memberaxis for guiding the cable; wherein the cable guide surface terminatesat first and second ends; wherein the cable guide member includes afirst cable guide member abutment; and wherein the frame includes aframe abutment for contacting the first cable guide member abutment andfor limiting a range of motion of the cable guide member.
 29. Theapparatus according to claim 28 wherein the cable guide surface has anapproximately semicircular shape.
 30. The apparatus according to claim28 wherein the cable guide member has an approximately semicircularshape.
 31. The apparatus according to claim 28 wherein the cable guidemember includes a bounded opening which forms the first cable guidemember abutment, and wherein the frame includes a projecting memberwhich forms the frame abutment.
 32. The apparatus according to claim 28wherein the cable guide member includes a second cable guide memberabutment, and wherein the frame abutment is disposed between the firstand second cable guide member abutments for contacting the first andsecond cable guide member abutments and thereby limiting a range ofmotion of the cable guide member.
 33. The apparatus according to claim32 wherein the cable guide member includes a bounded opening which formsthe first and second cable guide member abutments, and wherein the frameincludes a projecting member which forms the frame abutment.
 34. Anapparatus for guiding a cable comprising:a frame; a cable guide membermounted to the frame for rotation around a guide member axis, whereinthe cable guide member includes a curved outer peripheral cable guidesurface disposed radially outwardly from the guide member axis forguiding the cable; wherein a portion of the cable guide member has anoncircular outer peripheral surface when viewed along the guide memberaxis; and a bearing disposed radially outwardly from the outerperipheral cable guide surface, wherein the bearing has a bearing cableguide surface.
 35. The apparatus according to claim 34 wherein the frameincludes a cable duct having a duct opening that aligns between theouter peripheral cable guide surface and the bearing, and wherein thebearing is aligned between the cable duct and the outer peripheral guidesurface.
 36. The apparatus according to claim 35 wherein the ductopening substantially tangentially aligns with the outer peripheralcable guide surface.
 37. The apparatus according to claim 34 wherein thebearing comprises a roller.
 38. The apparatus according to claim 37wherein the roller rotates around a roller axis, wherein the roller axisis substantially parallel to the guide member axis.
 39. The apparatusaccording to claim 34 wherein the cable guide surface terminates at aradially inwardly extending abutment when viewed along the guide memberaxis.
 40. The apparatus according to claim 39 wherein the cable guidesurface has a substantially semicircular shape when viewed along theguide member axis.
 41. An apparatus for guiding a cable comprising:aframe; a cable guide member mounted to the frame for rotation around aguide member axis, wherein the cable guide member includes a curvedouter peripheral cable guide surface disposed radially outwardly fromthe guide member axis for guiding the cable; wherein a portion of thecable guide member has a noncircular outer peripheral surface whenviewed along the guide member axis; a first bearing disposed radiallyoutwardly from the outer peripheral cable guide surface, wherein thefirst bearing has a first bearing cable guide surface; a second bearingdisposed radially outwardly from the outer peripheral cable guidesurface, wherein the second bearing has a second bearing cable guidesurface; and wherein the first bearing is spaced apart from the secondbearing in a circumferential direction of the outer peripheral cableguide surface.
 42. The apparatus according to claim 41 wherein the firstbearing and the second bearing are disposed at the same radial distancefrom the guide member axis.
 43. The apparatus according to claim 41wherein the outer peripheral cable guide surface, the first bearingcable guide surface and the second bearing cable guide surface lie in acommon plane.
 44. The apparatus according to claim 41 wherein the firstbearing comprises a first roller, and wherein the second bearingcomprises a second roller.
 45. The apparatus according to claim 44wherein the first roller rotates around a first roller axis, wherein thesecond roller rotates around a second roller axis, wherein the firstroller axis and the second roller axis are both substantially parallelto the guide member axis, and wherein the outer peripheral cable guidesurface, the first bearing cable guide surface and the second bearingcable guide surface lie in a common plane.
 46. The apparatus accordingto claim 41 wherein the frame includes a first cable duct and a secondcable duct.
 47. The apparatus according to claim 46 wherein the firstcable duct comprises a first tubular member through which the cablepasses, and wherein the second cable duct comprises a second tubularmember through which the cable passes.
 48. The apparatus according toclaim 41 wherein the first cable duct includes a first opening thatsubstantially tangentially aligns with the outer peripheral cable guidesurface, and wherein the second cable duct includes a second openingthat substantially tangentially aligns with the outer peripheral cableguide surface.
 49. The apparatus according to claim 46 wherein the firstbearing is disposed in close proximity to the first cable duct, andwherein the second bearing is disposed in close proximity to the secondcable duct.
 50. The apparatus according to claim 46 wherein the firstbearing is aligned between the first cable duct and the outer peripheralguide surface, and wherein the second bearing is aligned between thesecond cable duct and the outer peripheral guide surface.
 51. Theapparatus according to claim 50 wherein the first cable duct includes afirst opening that substantially tangentially aligns with the outerperipheral cable guide surface, and wherein the second cable ductincludes a second opening that substantially tangentially aligns withthe outer peripheral cable guide surface.
 52. The apparatus according toclaim 51 wherein the first bearing comprises a first roller, and whereinthe second bearing comprises a second roller.
 53. The apparatusaccording to claim 52 wherein the first roller rotates around a firstroller axis, wherein the second roller rotates around a second rolleraxis, wherein the first roller axis and the second roller axis are bothsubstantially parallel to the guide member axis, and wherein the outerperipheral cable guide surface, the first bearing cable guide surfaceand the second bearing cable guide surface lie in a common plane. 54.The apparatus according to claim 46 wherein the first cable duct isspaced apart from the second cable duct.
 55. The apparatus according toclaim 54 wherein the first cable duct comprises a first tubular memberthrough which the cable passes, and wherein the second cable ductcomprises at second tubular member through which the cable passes. 56.The apparatus according to claim 55 wherein the first bearing comprisesa first roller, and wherein the second bearing comprises a secondroller.
 57. The apparatus according to claim 56 wherein the cable guidemember is substantially exposed.
 58. The apparatus according to claim 57wherein the first and second rollers are substantially exposed.
 59. Theapparatus according to claim 41 wherein the cable guide surfaceterminates at first and second ends.
 60. The apparatus according toclaim 59 wherein the cable guide surface has an approximatelysemicircular shape.
 61. The apparatus according to claim 59 wherein thecable guide member has an approximately semicircular shape.
 62. Theapparatus according to claim 59 wherein the cable guide member includesa first abutment, and wherein the frame includes a second abutment forcontacting the first abutment and for limiting a range of motion of thecable guide member.
 63. The apparatus according to claim 62 wherein thecable guide member includes a bounded opening which forms the firstabutment, and wherein the frame includes a projecting member which formsthe second abutment.
 64. The apparatus according to claim 59 wherein thecable guide member includes a first abutment and a second abutment, andwherein the frame includes a third abutment disposed between the firstand second abutments for contacting the first and second abutments andfor limiting a range of motion of the cable guide member.
 65. Theapparatus according to claim 64 wherein the cable guide member includesa bounded opening which forms the first and second abutments, andwherein the frame includes a projecting member which forms the thirdabutment.
 66. The apparatus according to claim 41 wherein the cableguide surface terminates at a radially inwardly extending abutment whenviewed along the guide member axis.
 67. The apparatus according to claim66 wherein the cable guide surface has a substantially semicircularshape when viewed along the guide member axis.